1. Field of the Invention
The present invention generally relates to an image processing unit, and more particularly to an image processing unit suitable for an image recording and regenerating unit, such as a digital camera, which can thin out an image data inputted by means of a CCD imaging device with a multiple pixels and display a moving image according to a resolution of a display unit.
2. Description of Related Art
An art for obtaining an image data by converting an optical image into an electron image signal by means of an imaging device such as a CCD and processing the electron image signal is widely known. In Japanese Patent Provisional Publication No. 8-51509, when an A/D converter converts analog R, G and B signals into a digital signal, a sampling signal generating circuit thins out R and B data to reduce a data amount in order to enable the reduction of a memory capacity.
Conventionally, when an image data inputted from a single plate CCD with a multiple pixels is displayed as a moving image, the image data is properly thinned to reduce the image data in accordance with a resolution of a display unit. The reduction of the image data may be performed in various manners. For example, if pixels of the CCD are arranged in G-stripe arrangement, R (red) data, G (green) data and B (blue) data for all the pixels are generated (three-lined) from a CCD output data (one-line data) which has dot-sequential R, G, B, G, R, G, B, G, . . . color information outputted from an output part of a horizontal transfer passage and then the three-lined data are thinned out at an appropriate thinning rate.
On the other hand, if pixels of the CCD are arranged in Bayer arrangement, a method is usually adopted in which a one-line data of an RG line which has R, G, R, G, R, G, . . . color information or a GB line which has G, B, G, B, G, B, . . . color information is two-lined and then the two-lined data is thinned out.
These conventional methods, however, in which the whole data obtained from the output part of the horizontal transfer passage is inputted to a signal processing part, which three-lines (or two-lines) the whole data and then thins out the whole data, depend on a thinning function such as a signal processing LSI, a reduction function, a capacity of a built-in buffer and so on. In addition, as the number of pixels of a CCD rises with a demand for high image quality, a frequency of a clock for driving the CCD rises to acquire a resolution (an active resolution) for displaying a moving image. Signal processing with a clock with a high frequency increases the consumption of electricity.